The present invention concerns equipment for dental surgery, more particularly equipment for inserting dental implants, and chiefly the device specially designed to insert a dental implant before it is secured by pins in the maxillary bone.
A device of this type is described in French patent 94 06593.
This application describes an implant that is supported on the upper cortical bone of the maxilla and on the lateral cortical bones by pins, and a particular insertion device.
As for the implant, its body is pierced with bores approximately transverse to its axis, through which one or more cylindrical pins are passed. These pins are inserted into the maxilla through pre-drilled holes in this bone, and pass through the implant via the bores.
These pins, while providing additional supports in the lateral cortical bones, immobilize the implant rotationally around its axis. In other words, the implant cannot pivot on itself and its mounting in the bone is considerably reinforced.
As for the insertion device, it includes a positioning element designed to be attached to the body of the implant in a particularly precise position relative to the bores. This positioning element supports a drilling jig that guides the drill relative to the body of the implant during the drilling of the holes reserved for the pins.
There are known drilling jigs, for example in U.S. Pat. No. 3,981,079. They do not allow for a good adaptation to the anatomical variations of the jaw, or a precise axial insertion of the mounting means.
French patent 94 06593 partially mitigates these drawbacks. It is, however, cumbersome during insertion and during any change in its position, for example when the implant receives several mounting pins at different levels.
One object of the invention is to eliminate these drawbacks.
The subject of the invention is a drilling jig for a dental implant, equipped with a positioning element, particularly an implant having at least one bore designed to receive a pin, said jig having means for locking it into a precise position on such a positioning element, at least one cylindrical pin guiding channel, and means for axially positioning said channel relative to a bony wall receiving an implant pin, characterized in that said axial positioning means include at least one elongated piece or sleeve, of defined length, which contains said channel and is movable along its axis in a jig body that guides it so that it can be brought, at a specially adapted end, in contact with the bony wall.
Preferably, the cylindrical channel also forms a drilling tool guide.
According to a currently preferred embodiment, the positioning element is produced in the form of a tube with a rectilinear axis, open at both ends. It includes an end part having a cross section shaped and sized so as to fit into an axial recess of corresponding cross section, open at the top, provided in the body of the implant. Said end part includes on one of its surfaces a relief, projection or recess designed to cooperate with the relief, recess (or projection) of corresponding shape provided in the wall of the recess of the body of the implant. The latter arrangement plays the role of a xe2x80x9ccorrectorxe2x80x9d, thus preventing any angular positioning error between the positioning tube and the body of the implant.
Inside its recess, the positioning tube has a conical support surface for the countersunk head of a screw, whose threaded barrel extends outside the tube at the end comprising, for example, a polygonal part. This threaded barrel is designed to be screwed into a corresponding threaded axial blind bore provided in the body of the implant behind said recess of polygonal cross-section.
Again according to a preferred embodiment, the tubular positioning element has a vertical lateral slot. The hole and slot of the positioning element are designed to receive, without play, the corresponding elements of the drilling jig. When the latter is in place inside the positioning element, the practitioner can immobilize it with a mechanical locking mechanism, for example a screw.
The male elements of the drilling jig, i.e. the cylinder and bit, that are inserted into the positioning element are extended at their periphery by a flat part whose profile is, for example, cut in a Z shape.
The upper flat part adjoins the cylinder and the vertical bit that are inserted into the positioning element. The vertical part is pierced in its bottom area with holes, the number of which preferably corresponds to the number of pins that the implant used includes, the axes of which precisely correspond to the axes of these holes. It is possible to slide, into each hole, a guide sleeve of clearly defined length having a thin, conical end that can come into contact with the bone. The surgeon places this sleeve in the hole that corresponds to the pin he is inserting. The body of this guide sleeve, which follows this conical part, is tubular in order to serve as a guide for various instruments, listed below. To facilitate the insertion of these instruments, the continuation of the body of the sleeve is open so that the surgeon can insert them in turn, as needed. The sleeve is long enough for the insertion of these instruments to take place outside the patient""s mouth.
In a series of operations as preferably adopted, once the implant has been placed in its cavity bored into the maxillary bone, it can be oriented by pivoting the drilling jig, and hence the implant, relative to the teeth. The choice of its angular orientation is left up to the judgment of the practitioner. When it has been determined that he will proceed with the drilling of the first hole for receiving a pin, he incises the gum by inserting a trocar into the sleeve, then slides the sleeve along the trocar until it contacts the bone. The small wound left by the trocar is minimal and its ulosis occurs very quickly. The drill is inserted into the sleeve in place of the trocar, and it is guided by the sleeve. The sleeve is also used to insert the pin. The latter has at one end a threaded blind hole, into which a pin holder is screwed. The pin and pin holder assembly takes the place of the drill once the drilling of the bone is finished. The pin is impacted using a small surgical mallet to hit the pin holder.
The pin having been inserted, it is released from the pin holder by being unscrewed.
Once the first pin has been set, the sliding sleeve is inserted into a second hole of the drilling jig in order to create a second hole in the bone, unless a second sleeve has been provided.
The obtainment of contact between the sleeve and the jaw bone provides great precision in the drilling of the holes and the insertion of the pins, and as explained below, this allows easy measurement of the length of the holes drilled into the bone.
The fact that the drilling jig is composed of two elements, i.e. the body of the jig and the sliding sleeve, means that the practitioner does not have to remove the jig from the positioning element in order to move it into another position for creating a second hole in the bone, as is the case in the jig described in French patent 94/06593. Only the sleeve is moved, which is much easier and faster. Furthermore, this configuration makes it possible to adjust the jig based on the thickness of the bone, unlike the guide described in U.S. Pat. No. 3,981,079.
In order to allow the practitioner to adapt to his patient""s morphology, it is advantageous to provide him with a set of several pins of the same size and shape, but of different lengths. The practitioner would thus be able to choose from these pins the one whose length approximately corresponds to the length of the hole or holes drilled into the bone. The measurement of this length can be determined from graduations on a tool, for example the drilling tool, by referring to a reference mark located on the sliding sleeve.
It may sometimes be necessary to remove one or more pins that have been inserted. Under these conditions, the jig being inserted into the implant holder, the practitioner screws the pin holder back into the pin, then exerts on it a traction supplied by a system generating an extracting force, a lifting screw for example, which is braced between the rear part of the sleeve and the knob that ends the pin holder.
In a preferred embodiment, the jig is configured so that the sleeve can pivot around a point located near its posterior part, so that it can be inserted, as desired, by its anterior part into any of the holes in the jig body. In this case, the passages or bores of the implant have inclined axes that converge at the pivot point. This makes it possible, in particular, to use only one sleeve, which is retracted only a short distance in order to move from one hole to another.
To this end, the flat part of the jig body has a profile, for example cut in a Z shape, whose vertical part, pierced with holes, is extended by a lower part hollowed out by a chute that guides the sleeve and allows it to pivot.
In another embodiment, which makes it possible to have parallel holes, it is necessary either to have one sleeve per hole, or to remove the sleeve from one hole in order to sink it into another hole, keeping in mind that the holes must be long enough to provide, by themselves, a precise guiding of the sleeve.
It is possible to provide means for adjusting the height, i.e. vertically, of the position of the jig on the positioning piece, for example via the insertion or removal of a removable shim. This allows the jig body to have only a limited number of holes, for example just one or two, while making it possible to align the jig with one or more additional bores of the implant by modifying the vertical position of the jig.
Other advantages and characteristics of the invention will emerge through the reading of the description that follows, written in reference to the attached drawings in which:
FIG. 1 is a top view of the positioning element.
FIG. 2 is a front view and a vertical section in the plane A0 of FIG. 1.
FIG. 3 is a front view of an implant in the process of being set into a maxillary bone represented in section with the gum that covers it. The implant supports the positioning element, which is attached to the drilling jig into which the sliding sleeve has been inserted.
FIG. 4 is a view of the sleeve.
FIG. 5 is a view of the pin holder.
FIG. 6 is a view in perspective of a maxillary bone holding an implant secured by 3 pins; it supports the positioning element and the drilling jig.
FIG. 7 gives a view of the pin configured according to the invention.
FIG. 8 is a view of the pin extracting instrument.
FIG. 9 is a front view according to a variant of the device. A drilling tool is present in the sliding sleeve.